If the FS Recognizer’s UDFS objects are in use, the UDFS file system has
not been loaded - FS Recognizer is a “stand in” driver that is used to
defer loading of the regular file system until it is needed. To
determine more would require a bit of work with the debugger (e.g.,
check and see if the recognizer is being called to mount the volume.)
If its not being called, then the next “trick” would be to force the
loading of UDFS (which would then cause registration, which would then
mean it gets called prior to NTFS.) Seriously, this is something that
you should be able to figure out in about 10-15 minutes with a kernel
debugger attached (I’ve had to do this before.) Look at the fs
recognizer’s device object, set a break point in its fs control function
and watch to see if it gets called with the UDFS recognizer object. If
it doesn’t then do the same thing to NTFS and watch its return code -
that’s going to be the key to the whole thing.
I’m not sure how the service control manager handles disabled drivers
anymore. If you can’t start it through the SCM, you’ll need to call
ZwLoadDriver directly to accomplish this.
Regards,
Tony
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
Looking forward to seeing you at the next OSR File Systems class in
Boston, MA April 18-21, 2006 (note new date - MS scheduled plugfest the
same week again.)
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com http:
Looking forward to seeing you at the next OSR File Systems class in
Boston, MA April 18-21, 2006 (note new date - MS scheduled plugfest the
same week again.)
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Saritha Vinod
Sent: Tuesday, March 07, 2006 1:23 AM
To: ntfsd redirect
Subject: Re: FW: [ntfsd] Does windows detects UDF formatted hard disk?
Hi Tony,
Thanks for the information.
I checked in our Windows 2000 machine also. As you said, the UDFS file
system has two device objects for FILE_DEVICE_DISK_FILE_SYSTEM and
FILE_DEVICE_CD_ROM_FILE_SYSTEM. Hence it would mean that it should be
given the opportunity to mount on disk as well as CD/DVD devices, right?
As you said, the last registered file system will be called first. So
how can we change the order in which the registration happens?
As far as changing the load order is concerned, what I observed is that,
a file system recognizer is registered with a start type 1(system start)
and group “boot file system”. The fs_rec has device objects
like"UdfsDiskRecognizer" and “UdfsCdromRecognizer”. The actual UDFS file
system driver has a start type of 4(disabled), which will be called by
the recognizer. So in this case how can we make the “UdfsDiskRecognizer”
to be called first to recognize the volume?
Also NTFS does not have a recognizer. Hence does it mean that NTFS is
always being called first to mount on a device?
Thanks,
Saritha.
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com]On Behalf Of Tony Mason
Sent: Tuesday, March 07, 2006 1:14 AM
To: Windows File Systems Devs Interest List
Subject: RE: [ntfsd] Does windows detects UDF formatted hard
disk?
Each file system implementation is free to decide how it
recognizes its own file system type. The UDFS file system (at least on
my XP box) has registered for both CD and DISK mount events, so I would
assume it can recognize a UDFS formatted disk drive type. With a tool
like objdir or winobj or the debugger, you should be able to determine
what the UDFS driver has registered as well (the device objects with
names have normally been registered for mount events.)
The media type does matter - Windows only supports mount on four
media types: FILE_DEVICE_DISK, FILE_DEVICE_TAPE, FILE_DEVICE_CD_ROM,
FILE_DEVICE_VIRTUAL_DISK - with the latter being “lumped into” the same
file system type as the first one. File systems of type
FILE_DEVICE_DISK_FILE_SYSTEM are given the opportunity to mount
FILE_DEVICE_DISK or FILE_DEVICE_VIRTUAL_DISK media. File systems of
type FILE_DEVICE_CD_ROM_FILE_SYSTEM are given the opportunity to mount
FILE_DEVICE_CD_ROM, etc.
To achieve this, the file system must create a unique device
object and register that device object with the I/O Manager
(IoRegisterFileSystem). The I/O Manager then maintains a LIFO call
table of file systems (last registered, first called) that are invoked
to check a media device and determine if the volume in question has the
right format.
One issue I’ve seen interfere with mounting in the past is that
the I/O Manager is very sensitive to errors returned by the mounting
file system. It expects STATUS_UNRECOGNIZED_VOLUME (see FatMountVolume
in fsctrl.c for FAT). Other errors can (and do) cause mounting
problems. For example, we had an FSD that was written to work with WORM
media. If NTFS were asked to mount the volume first and it attempted
to read an unrecorded area on the media it would get an I/O error
(indicating that the sector had not yet been recorded). NTFS would
report this error to the I/O Manager and the I/O Manager would abort the
mount processing - so our file system never was given an opportunity to
mount. Different media, or different load ordering and the mount
proceeded correctly. This was many years ago and at the time I lobbied
for changes to the I/O Manager to be a bit more liberal in its decision
to continue mount processing but was told that this wouldn’t happen
because it only affected a non-MS file system.
Bottom line: mount processing is an elaborate dance with
multiple players, each of whom must behave in a proscribed manner. A
failure to do so may lead to cases where a volume may not behave the way
that you expect.
Regards,
Tony
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com http:</http:>
Looking forward to seeing you at the next OSR File Systems class
in Boston, MA April 18-21, 2006 (note new date - MS scheduled plugfest
the same week again.)
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Saritha Vinod
Sent: Monday, March 06, 2006 7:16 AM
To: ntfsd redirect
Subject: [ntfsd] Does windows detects UDF formatted hard disk?
Hi all,
I am trying to format a hard disk partition using UDF file
system. Since windows 2000 does not have write support for UDF, I
formatted using Linux and was able to read and write to it. The UDF
version used was 1.50. I tried accessing that partition again in
Windows. But windows failed to recognize it and showed that it is not
formatted. Can anybody please tell me the reason for this? Is it that
windows will not recognize UDF on hard disk, since it tries to mount UDF
only for CD/DVD devices?
Is the media type in anyway related to this behaviour?
Thanks in advance.
Saritha.
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